Tips for seamless DIY drywalling

Mike McClintock, SPECIAL TO THE TRIBUNECHICAGO TRIBUNE

Drywall suppliers can deliver the unwieldy panels almost anywhere -- even with a crane through second-story windows. Without the hassle of hauling, that makes drywalling a new room or recovering a damaged wall a reasonable do-it-yourself project -- with just a few stumbling blocks.

Here are some of the false steps and how to fix them, or better yet, avoid them altogether.

The wrong framing. Wet lumber (over the acceptable standard of 19 percent moisture content) can wreck even the best drywall job. Finished seams and spackled nail heads give the appearance of smooth plaster to start. But as wet lumber dries out in he wall it can twist enough to pop nails and crack open joints between panels.

The wrong panels. Standard panels work on most walls. But water-resistant panels (normally green-tinted) include an asphalt mix in the gypsum and a chemical in the surface paper to stand up better in high-moisture areas like kitchens and baths.

Another special type, fire-resistant panels, increase the amount of time wallboard stays intact when exposed to fire. They offer a better safety margin than standard panels in furnace or utility rooms -- and may be required by code.

The wrong fasteners. You can use drywall nails to hang wallboard. And if the supporting lumber is dry and stable the heads probably will hold the panels tightly without popping. But for considerably more holding power, use threaded drywall screws.

Incomplete nailing. If you discover loose or sagging panels during installation, press firmly on the panel while driving home extra nails or screws. Don't rely on the fastener to pull the panel into place, particularly on ceilings.

Unprotected corners. Drywall corners that protrude into the room are vulnerable to damage. A covering of paper tape and spackle is fine for appearance sake, but doesn't offer the extra strength of corner guard- an L-shaped metal strip that covers the drywall edges.

Raised joints. Bulging seams, called crowing, can result when taping compound is painted before it dries. Because it's obvious when compound is dry (it turns a light yellow color and powders under sanding), painting too soon is easy to avoid. More often, the swelling is caused by using too much compound under the joint tape, or by leaving large, compound-filled gaps between panels. The remedy is to sand down the crowns taking care not to scuff the drywall paper too much. To prevent crowning, fit drywall panels together without gaps and use only enough compound in the embedding layer to seat and smooth over the tape.

Tape bubbling. Unless compound is spread thoroughly over the seam between panels, dry spots can be left where the paper tape does not make contact, and they're likely to bubble later on. The key is to spread the embedding coat of compound evenly, and, when smoothing the tape in place, to watch for a complete and uniform color change.

With continuous contact, the dry, light-colored tape darkens as it soaks up moisture from the compound.

To repair a bubbled seam, use a sharp utility knife to cut away the dry paper and fill the damaged area with compound. Where bubbling pops up in many areas on the tape, the best bet is to remove it, sand off excess compound and start again.